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Campus Crops is a student run urban gardening initiative at McGill University's downtown campus. We want to grow food on campus, by students, for students. We have been running garden behind the School of Environment building at 3534 University since 2007. In 2009 we started a terrace garden behind the James Administration building. We're really excited to keep improving these two spaces, and need lots of helping hands for the summer ahead! Get in touch and get gardening!

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Sunday, May 11, 2014

Seeds, germination, and seedlings

Germination test

A germination test
is a good way to determine the approximate percentage of viable seeds in a
given batch of seeds. It is especially useful for seeds saved by amateur
gardeners or for old batches of seeds.

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To do a germination
test, simply take a representative sample of about 10-20 seeds of a seed batch.
To obtain a representative sample, simply pick the seeds at random: picking
only the best looking or biggest seeds from the batch would not be a good way
to test the whole batch. Put the seeds between two layers of wet paper towel or
wet biodegradable coffee filter, place in a sealable plastic bag, and let sit
in a dark and warm place. Keep the paper material moist at all times, without
adding too much water in the bag. Every few days, check the seeds to see if any
sprouted yet, and compare the time of germination to what’s written on the seed
packet. Seeds that do not sprout at all are not viable, and seeds that sprout
are viable. The germination rate is the percentage of viable seeds in the
sample (i.e. seeds that sprouted).

Soaking seeds

Soaking seeds before
planting them helps get a faster and more uniform germination. Seeds need water
to soften up and get activated to initiate growth. Yet, when sowed dry in the
soil, they get less water at a time and at a less uniform rate in space and
time (if the soil dries between watering sessions, or if an unequal soil
structure or planting depth doesn’t allow as much water to reach all seeds
equally, for example). When soaked, seeds get to absorb all the water they need
before being planted in the soil.

To prevent fungal
and microbial growth, seeds can be rinsed with a 1 part bleach to 10 part water
solution before soaking.

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To soak seeds,
simply put them in clean lukewarm water. It is preferable not to allow
seeds to germinate before planting, as it is easier to contaminate the sprouts
once they have germinated. For this reason, never let seeds to soak for more
than 24 hours, unless they don’t look ready. A well-soaked seed will have
swollen and lightened in color, and its hull will have softened. Beet seeds
have a very hard shell and it is better to soak them for a full 24-hour, if not
more. Likewise, large bean seeds may need more than 24 hours of soaking.

Thoroughly submerge
the seeds and place them in a warm, dark spot. Small seeds tend to stick to
fingers when wet, so they can be put in a water bottle with their soaking water
and squeezed out to plant. They can also be put to soak between moist layers of
toilet paper or biodegradable coffee filters placed in a hermetic bag, and then
planted along with the paper material. Other people also prefer to mix the wet
seeds with wet sand and to sow the whole mix. Bigger seeds can be planted by
hand, and are also the ones that benefit the most from soaking (since they need
more water).

Seeds should be
planted right away after being soaked. Once the soaking is done, seeds
should not be left to dry or to soak longer before planting.

Seeds will need a
rich, well-aerated, loose, and moist but not wet soil for planting. If the soil
is too hard or too compact, dig a large hole where lighter soil will be mixed
with the garden soil. This will allow the seeds to germinate without too much
difficulty while encouraging strong root growth (if the roots are too weak, the
harder soil will be impossible to penetrate and will act as a container for the
plant).

A good potting mix
should include the following : water-retaining fibres such as peat moss or
coconut fibres, solid organic fertilizer, perlite, and compost. Using 5 gallons
buckets, the recipe is :

-3 buckets peat moss

-2 cups organic
fertilizer

-1 bucket perlite

-3 buckets compost

Wet the mix before
using.

Sowing seeds

Whether they are
sowed directly in the garden or to be grown as seedlings, seeds are planted the
same way. It is also useful to keep a propagation record detailing the sowing
date, the germination date and the rate of success, as well as the date when
seedlings are ready for transplanting. This way, it is easier to notice what
went right and what went wrong, and adjust accordingly the following year.

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After soaking the
seeds, place them in the soil at the recommended depth. As a rule of thumb,
seeds should be planted at a depth of twice their diameter (no more than 3-4
times the diameter), but it is better to look on the seed packet or the
internet for specific instructions. Very small seeds can simply be sprinkled on
the soil surface. If planted too deeply, the seeds may germinate but die before
reaching the surface. If planted too shallowly, wind or rain may blow or wash
the seeds away before they sprout. When planting during the summer, sow the
seeds slightly deeper, as the soil dries quicker.

Gently tamp down the
soil over the seeds to allow good contact between the soil and the seeds. Water
to moisten the soil. It is better to plant seeds with half the recommended
spacing and then thin once they germinate, in order not to leave empty spaces
in the garden due to failed germination. Similarly, preparing more seedlings
than necessary is useful in case some seeds do not germinate (seeds rarely have
a 100% germination rate).

Make sure that you
don’t water the seeds too much and that there is good aeration (in the aerial
parts of the plants and in the soil), otherwise some fungal diseases might
develop and kill the plant not long after it germinates. When watering, use a
gentle spray to avoid disturbing the soil and seeds. A light mulch over newly
planted seeds can help conserve moisture.

Sowing techniques

Rows: using a
hoe, dig a straight furrow, plant.

Wide rows:
seeds can be scattered over the surface or planted in blocks (i.e. the same
crop will be planted in a same block instead of a row, so that a bed will be a
succession of blocks instead of row of crops)

Hills: for
cucurbits and corn. Not mounds; hills are groupings of seeds, not actual hills
(which result in dry soil). Sow 4-5 seeds in 6-8 inches circles, using
recommended spacing. Thin to 3 plants later.

Square-foot:
1-by-1 ft squares, single crop at a time, the amount of plants per square
depends on the recommended spacing (minimum 1 large plant, like a tomato plant,
except for squash which use at least 2 squares each)

Taking care of
and hardening the seedlings

Growing conditions
for seedlings include proper soil temperature, exposure to sunlight,
fertilizing (if necessary), soil mix, and watering. Normally, seedlings will
grow best in a constant environment, with 12-16 hours of light per day,
constant temperatures, no wind, good aeration and a constantly moist but not
wet soil. Heating may be necessary, but more watering will be needed for warmer
temperatures. Give the seedlings a quarter-turn each day for even sunlight
exposure.

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Seedlings need to be
hardened before being transplanted in the harsh outdoors. As they’ve been
growing in a controlled environment, with no wind, warm and constant
temperatures, and with a constant supply of water, indoor-grown seedlings are
more fragile than seedlings growing from garden-sowed seeds. It is thus
necessary to make them hardier to the natural elements before they face the
sad, sad reality of this world. Do not transplant seedlings if they show signs
of stress or wilting; allow them to recover first, by putting them back into an
artificial environment if needed.

First, to thicken
seedlings stems, one can simply brush the seedlings with their hand a few times
a day as they are growing indoors. This can be done as often as possible, by
making sure not to break, weaken or damage the seedlings.

Then, one to two
weeks before transplanting them, seedlings need to be gradually accustomed to
direct sunlight, desiccation, wind, temperature changes, etc. The first step is
to take the seedlings outdoors for a few hours in a shady, protected area. Over
the next few days, seedlings should be exposed gradually to direct sunlight and
wind for longer periods. They should also be allowed to go a little dry between
the watering during the hardening process.

Transplanting
seedlings

When transplanting, one
needs to be careful not to break or damage the aerial parts (stem, leaves) of
the seedlings, but also, more importantly, not to disturb roots to allow a
quick recovery after transplantation. Water seedlings before transplanting.

Try to transplant in
the late afternoon or on a cloudy day, so as to avoid stressing seedlings with
excessive heat. If this is not possible, cover the seedlings with a thin layer
of straw to shade them a bit.

If using
biodegradable pots (e.g. peat pots), the pots can be transplanted with the
seedlings, but the pots need to be completely buried, as they will otherwise
act as a wick that will draw moisture from the soil on windy and/or dry days.

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To remove a seedling
from a plastic pot without disturbing the roots, place a hand over the pot in
order to receive the soil block and to secure the seedling without breaking it.
Then, squeeze and/or tap gently the bottom of the plastic pot too loosen the
soil, and finally flip the pot upside-down to let the seedling fall gently in your
hand. If the root ball is tangled up, gently untangle the external roots before
transplanting. Seedlings can also be gently pulled by the leaves to get them
out of their pot.

Make sure that the
transplant hole contains loose soil with compost (but not too much). If the
garden soil is very compact or very different from the planting soil used for
the seedling, dig a large hole and mix garden soil with the planting mix. This
will act as a transitioning zone so the seedling roots do not encounter a physical
or chemical wall as they grow.

Water the hole
before adding the seedling. The seedling should be transplanted so its stem is
slightly under soil level (basically you want the surface of the root ball to
be level with the garden soil surface). Some seedlings can be buried up to
their first true leaves, like tomatoes that will grow additional roots from
buried stems. Surround and cover the seedling roots with soil, and tamp gently
to ensure good contact between the root ball and the soil. Water a bit more if
necessary.

Early transplants
may need a cover to avoid frost. Make sure, though, that it is well aerated,
otherwise the seedlings may suffer from heat shock. All seedlings should be
mulched lightly after transplantation to conserve moisture and reduce
transplant shock.

Do not allow
seedlings to flower. Remove the flowers, as blooming needs a lot of energy that
would be better invested in root or stem growth at this stage.

Planning is
important

Before planting time
(March) comes, a planting calendar must have been done. Indeed, not all plants
are sowed/transplanted indoors/outdoors at the same time, depending on the soil
temperature. An approximate calendar can be made using the average last frost
date (LFD) of the locality.

Soil temperature

A more accurate
method to sow/transplant at the right time is using soil temperature. Soil
temperature can be measured with any glass bulb thermometer. Make sure to make
multiple readings during the day (at least one in the morning and one in the
late afternoon) at the recommended sowing depth. Make a pilot hole with a
screwdriver for the thermometer to avoid breaking it. When measuring the
temperature, sunlight can skew the measurement, so make sure to shade the
thermometer and to give it some time to get an accurate measurement before
reading it.